Through refinements in circuit design and semiconductor processing methodologies it has now become possible to integrate in a monolithic miniaturized packaging scheme substantially all of the components of which an RF communication system may be configured. As the demand for higher operational frequencies and bandwidth utilization has increased, however, the use of the support/housing structure as a signal processing environment and a radiation site has been limited by the size of and the unwanted mutual coupling between the antenna elements and the components of adjacent signal processing networks. As a consequence separate supports are conventionally employed for the antenna elements and the microwave chip carriers that contain the signal processing circuitry, yielding an overall packaging scheme that is large-sized and therefore not necessarily optimized for use with complex communication/avionics equipment, such as that incorporated in high performance military aircraft. Moreover, for such applications, the unique dimensional tolerances and heat transfer characteristics of the devices have effectively prevented a standardized packaging scheme. Instead microwave device housings have been typically custom-designed thereby constituting a significant portion of production cost.
One proposal to standardize the packaging of such circuits has been to use conventional TO-style, plug-in cans, originally employed for discrete devices and in the early days of integrated circuit development. Unfortunately, however, because the conventional TO-style can is designed for components that operate at frequencies considerably less than the signal processing bandwidth of present day microwave (e.g. GaAs-resident) devices, it has a practical upper operational frequency limit on the order of one to three GHz or less.
In our copending U.S. patent application, Ser. No. 888,934 entitled "Plug-in Package for High Speed Microwave Integrated Circuits", filed July 24, 1986, now U.S. Pat. No. 4,951,011, issued Aug. 21, 1990, and assigned to the assignee of the present application, there is described an improved TO-style, plug-in can configuration designed for present day high frequency (e g 10-40 GHz) microwave signalling applications. Specifically, through an improved pin/glass seal interface, what would otherwise be an impedance mismatch between a monolithic microwave integrated circuit (MMIC) and the external world is effectively `tuned out`, so that the sought after standardization aspects of conventional TO-style cans are retained, thereby facilitating the interfacing of the packaged circuit components with a variety of signal transmission networks.